Global and Arctic climate engineering: numerical model studies

Ken Caldeira & Lowell Wood

Through a mathematical model of global (generally Arctic) climate engineering, the results that a reduction of insolation (solar radiation) would have on our climate are simulated. Although the results do not imply climate change reversal, it seems possible that such reduction could engineer our climate similarly to one with a lower CO2 concentration.

The temperature changes resulting from two experimental simulations: (a) and (b) being our climate with twice the CO2 concentration than the pre Industrial Revolution era, and (c) and (d) being the climate with a uniform 1.84% reduction of insolation. The left column shows the temperature change relative to the PRI era, while the right column shows the percentage of the globe with a statistically significant change.

Changes in precipitation: In the same two experimental simulations. (a) and (b) are again our climate simulated with twice the CO2 concentration from before the Industrial Revolution, while (c) and (d) are the climate with a 1.84% uniform reduction in insolation. The left column shows the precipitation change relative to pre Industrial Revolution levels, while the right column shows where in the world this change is statistically significant.

Abstract

We perform numerical simulations of the atmosphere, sea ice, and upper ocean to examine possible effects of diminishing incoming solar radiation, insolation, on the climate system. We simulate both global and Arctic climate engineering in idealized scenarios in which insolation is diminished above the top of the atmosphere. We consider the Arctic scenarios because climate change is manifesting most strongly there. Our results indicate that, while such simple insolation modulation is unlikely to perfectly reverse the effects of greenhouse gas warming, over a broad range of measures considering both temperature and water, an engineered high CO2 climate can be made much more similar to the low CO2 climate than would be a high CO2 climate in the absence of such engineering. At high latitudes, there is less sunlight deflected per unit albedo change but climate system feedbacks operate more powerfully there. These two effects largely cancel each other, making the global mean temperature response per unit top-of-atmosphere albedo change relatively insensitive to latitude. Implementing insolation modulation appears to be feasible.